The present invention constitutes a specific, needed improvement over the machine tool disclosed in U.S. Pat. No. 3,609,838 to H. Wiest.
In the Wiest patent, a pallet is carried by a rotary gear into rough alignment with successive, peripherally spaced machining locations. The pallet is connected to the gear by means of a "spring pack," wherein a spring urges the pallet and the parts loaded on the pallet vertically upwardly into spaced relation above the gear. At the machining location, the gear is halted, and hydraulically actuated clamping devices pull the pallet downwardly relative to the gear and against the load of the spring pack to fix the pallet to a machine base in accurate alignment for machining.
The spring pack must exert substantial force upwardly to enable the pallet and its load of parts to float above the gear during transport. This spring force must be overcome by the clamping mechanism in order to pull the pallet downwardly into clamped position at each machine station prior to machining. The spring load has proven to be critical in use, and each individual machine tool must be fitted with specific spring packs depending upon the weight of the pallet, the weight and number of the parts to be machined, etc. Additionally, the necessity of overcoming the spring force with the clamping elements reduces the net clamping force securing the pallet in position during machining.
It would be desirable from an economic and functional standpoint to eliminate the spring arrangement interposed between the pallet and the carrying gear.